1. Field of the Invention
The present invention relates to a method of planarizing a substrate suitable for remarkably planarizing a surface thereof, and to a magnetic head produced by using such a planarized substrate and a method of manufacturing the magnetic head.
2. Description of the Related Art
In recent years, devices formed on a substrate with thin film technology have been prevalent as various types of electronics are highly integrated and become smaller in size. For such devices using the thin film technology, it is important to mirror-finish a surface of a substrate, that is, to remarkably planarize the surface, in order to achieve improved characteristics and a higher integration.
An example of the devices formed on a substrate using the thin film technology is a so-called bulk thin film type magnetic head, which has a pair of magnetic core halves, each half including a non-magnetic substrate and a metal magnetic thin film obliquely deposited on the non-magnetic substrate. The paired halves are bonded integrally to each other with the one metal magnetic thin film abutting on the other such that a magnetic gap is formed between abutting surfaces. In addition, surfaces of the non-magnetic substrates on which the metal magnetic thin films are deposited are not in parallel with the magnetic gap.
In the bulk thin film type magnetic head, impedance can be reduced by setting a short magnetic path for the magnetic core formed of the metal magnetic thin films deposited on the non-magnetic substrates.
When the aforementioned bulk thin film type magnetic head is produced, the metal magnetic thin film is deposited on the surface of the non-magnetic substrate in which a plurality of grooves having slopes are formed at a predetermined interval to obtain the metal magnetic thin film not in parallel with the magnetic gap. Conventionally, the surface of the non-magnetic substrate on which the metal magnetic thin film is deposited has been mirror-finished through lapping using abrasive grains.
In producing the bulk thin film type magnetic head, however, the aforementioned lapping has difficulties in mirror-finishing inner surfaces of the grooves formed on the surface on which the metal magnetic thin film is deposited. Specifically, since the lapping relies on polishing works using abrasive grains to mirror-finish the surface of the non-magnetic substrate on which the metal magnetic thin film is deposited, it is difficult to remarkably planarize the inner surfaces of the grooves formed in the surface of the non-magnetic substrate, that is, slopes, sides, bottoms or the like inside the grooves. The lapping also takes excessive time to mirror-finish the inner surfaces of the grooves formed in the surface of the non-magnetic substrate. In addition, the lapping may involve a significantly complicated process for enhancing accuracy in forming the grooves formed on the surface of the non-magnetic substrate and mirror-finishing the inner surfaces of the grooves. Furthermore, in the lapping, it is difficult to mirror-finish the inner surfaces of the grooves formed in the surface depending on the materials of the non-magnetic substrate.